A light emitting diode (LED), a lamp, or a liquid crystal display (LCD) is generally used in a display section to present information about an internal combustion engine. This display section is responsive to amounts of oil and cooling water in the engine and flickers when they are reduced to levels below predetermined values. In this way, the abnormal condition is relayed to the driver, thereby preventing a condition such as burn-out, overheating, or the like of the engine.
The conventional control apparatus for the display of the internal combustion engine is provided with, for example, an oil level switch having a plurality of contacts. Each of these contacts is connected to an indicating lamp. A float with a magnet is adapted to be vertically movable in dependence on the amount of oil. A contact which is disposed at the position where it faces, or in other words is vertically aligned with, the float is turned on, so that the associated indicating lamp is lit. (This apparatus has been disclosed in Unexamined Japanese Patent Publication No. 86561/1973). According to the above apparatus, the vertical position of the float changes in accordance with the amount of oil, and indicating lamps are lit so that the amount of oil can be discerned by the driver.
However, in such an oil amount display apparatus, the oil level switch and indicating lamps are merely directly connected. When this apparatus is used in an outboard engine, the float always moves vertically due to the waves. Thus, there is the problem that one or more of the contacts are rapidly turned on and off and thus one or more of the indicating lamps are repeatedly turned on and off, so that the oil amount cannot be accurately indicated.
In addition, when the oil tank is attached to the outboard engine, the whole engine assembly has a fairly deep shape. To sequentially light up the indicating lamps, the contacts must be overlappingly attached within a predetermined range. Therefore, in the case of attaching the respective contacts at many positions from the top (the oil level when the tank is filled with oil) to the bottom (the level when the tank is empty), the number of contacts increases and at the same time it is necessary to provide additional space in the horizontal direction to overlappingly attach the contacts. Consequently, it is difficult to manufacture the oil amount display apparatus so that those contacts are inserted into a pipe and the float is attached to the outer periphery of the pipe and vertically moved. There is also the drawback that the outboard itself increases in size.
Further, even when a lot of indicating lamps are attached, only one of the lamps corresponding to the current vertical position of the float is ordinarily used at any given moment. Thus, there are the drawbacks that the efficiency of use of the indicating lamps is bad and the indicating effect to positively present the oil amount to the driver is small.
There has been known another display control apparatus in which the oil amount and the temperature of the engine are detected and the ignition apparatus is temporarily interrupted if the oil amount decreases to a level below a predetermined value or the engine temperature exceeds a predetermined value, thereby limiting the engine speed. Namely, when the oil amount is below a predetermined level, the oil level switch is turned on and the ignition apparatus connected to this switch is made inoperative, thereby limiting the engine speed. On the other hand, the engine temperature is detected by a heat sensor. When the engine temperature is above a predetermined value, the heat sensor is turned on and the ignition apparatus connected to this sensor is made inoperative, thereby reducing the engine speed. Upon limitation of the engine speed, the display section, consisting of light emitting diodes or the like, is lit up, thereby informing the driver about the abnormal condition of the oil amount or engine temperature.
However, when the engine is used at a speed below the predetermined speed, the display device is not lit, the ignition apparatus continues to operate and the engine speed is not limited. Thus, there is the problem that burn-out, overheating, or the like of the engine may occur.
The following technologies can be mentioned as prior arts of the present invention.
(1) JP-A 48-86561 PA1 (2) JP-A 57-131820 PA1 (3) JP-A 60-85210 (JP-A: Official Gazette of Japanese Patent Unexamined Publication) PA1 (4) Official Gazette of Japanese Utility Model Unexamined Publication No. 36510/1985